Peavey Valve King 212

You would think that a 10W resistor marked on the schematic as a safety device would mean that any wiring would be loomed away from it, not laying along its length. Another safety issue with these amps, I was trying to see where the chunky HT wire to the output amp was, but nothing obvious. It is in the grey ribbon umbilical , >500V rating on that stuff? I doubt it. 6 months old , no warning signs of crap solder used, no PbF / RoHS /N or even the CE mark for this , for export, 240V structured amp, just a wheelie bin with an X over it.

speaking of stupid symbols, what's the circle with an arrow possibly indicating some sort of rotation and a number "10" inside mean?

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bin

If you are talking of plastics moulding mark then the "hour" of the pointer is the month of the castings in 2010

Probably just one of the old amps where the volume does not go up to

11.

Anyone know how to read the plastic mouldings marks where it is 2 or 3 simple bars, not arrows, in 2 or 3 circles. It seems the bar is never central but pushed to one side , is that the arrow direction? Then if 2 circles first "2 o'clock", say, is 2002 and second "3 o'clock " say, is march. Then 3 dials is year/ month/ week ?

Saw one of these a while ago and had to hard wire the ribbon cable between pre-amp/power amp boards as it had arced/burnt the connectors.

One thing I particularly remember is the OPT input feed is connected via a plug and socket to the output PCB and, unlike most Peavey units, it is possible to connect this the wrong way round. This will result in all sorts of weird feedback/oscillations, particularly when playing with the "resonance" pot on the back panel.

This amp cost me a lot of time and frustration.

Gareth.

sorts

At least the OPT wires are proper 500V rating. I ' ve now marked that connector JIC. I imagine your ribbon problem was initially the euro-crap solder inside. I've pared off the HT wire and spiral wrapped some sleeving around it. The wiring to the standby switch will go the other side of the main caps not over the replaced 400R 10W dropper that had exploded to 3 bits in the conflagration.

I think it was actually the heater circuit that burnt the connector contacts, though I'm not 100% sure of that. I've seen this same burning on other equipment too, usually the high current PSU connectors, (Molex?).

Gareth.

A good cleaning and use of antioxidant electrical compound on the connections usually helps there.

Jamie

Hard wiring to bypass a poor design / poor choice of connector works a lot better IMHO. :)

Gareth.

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Over time sprung connections loose their spring. Sorted out someone's favourite amp last week, a number of crimp spade connectors inside, cut off and soldered in , should be fine for another 20 years

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current

I was wondering about the current rating through the ribbon for the op heaters but they are daisy-chained and then awkwardly connected to the pre heaters, confusingly. As this is only 6 months old perhaps a stock fault previously , the ribbon here is soldered either end

I seem to remember something odd about the heater circuit - is there not some kind of series/parallel thing going on? I seem to recall you can't pull one or more of the pre-amp tubes to leave just the phase splitter and o/p valves working.

It's possible I'm confusing this with another amp, but you have just rung a bell in my head.

Gareth.

Hmm, check the schematic here if you don't have one. (can't be arsed to seek further)

Seems the 4 o/p valves AND the phase splitter heaters are all in series. Got that wrong in my last post - you can't remove the output valves and see what the phase splitter is doing.

Not sure what or why is going on with V1 and V2, but I seem to recall if you pull the wrong one, the other gets a double dose of heater voltage so be careful.

Note also the feedback comes from the OPT output connected resonance and presence circuit. Hence the mega problems if the OPT input is connected out of phase.

This amp did cost me a lot of time, and it seems it is still doing so.

Gareth.

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yes very odd , at first sight all valve heaters pa and prea, .9A and .3A are daisy-chained in series but there is another ps tap off point labelled 6V or

6V1 for the high current tubes

Its confused because V3 splitter driver is physically on the op pcb, but all

3x .3 amp heater valves (6.3V setting) are in parallel for .9 amp total at node ( 6V or 6V1) and then in series with the 4 output valves, each at .9 amp so in effect current-wise 5x .9 amp in series and 5 x 6.3V supply

Maybe that's so they can use Mickey Mouse connectors/PCB traces at 1 amp capacity rather than have to hand wire proper heavy duty wires. Whatever, it doesn't seem to work very well.

Makes a bit more sense now though, cheers.

Gareth.

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.9

So anyone live swapping V1,2 or3 will get too much power to the heaters on the remainder . Or with heater failure in one triode may lead to a cascade of failures assuming the mate of the first failed one would be similarly disstressed.

Yep, I saw one 12AX7 glow far brighter than it should have done after pulling another, which is why I warned you to be careful!

Gareth.